Hello,
For your processor, have a look here :
https://www.intel.com/content/www/us/en/products/sku/197098/intel-xeon-silver-4210r-processor-13-75m-cache-2-40-ghz/specifications.html
The line of interest is "Total cores"
I don't know much regarding your configuration but if you use MS-MPI you can try the following command :
mpiexec -np 10 -aa -a "path_of_the_solver" i=input.k memory=
Deactivate hyperthread in the BIOS.
Best Regards,
Loïc